NBDE I - Dental Anatomy Problem

[drPheta]

What's the answer to this one? I thought it was "b" but I'm told otherwise. Isn't non-working to the side of the orbiting condyle? Therefore, in order for a mandibular supporting cusp to have guiding contacts during excursion on the lingual side of the facial cusp, it'd have to be on the non-working side... no? Am I crazy?

Here's the question and the picture... This is 1989 Dental Anatomy question #8


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The dentist placed a cast crown on a patient who has an ideal canine guided occlusion. The maximum intercuspal position (MIP) contacts are ideal; however, when the lateral movements were evaluated with an articulating paper, the following smudge marks were noted. The smudge mark labeled a,b,c represents which of the following contacts?

a. Working side
b. Non-working side
c. Protrusive
d. Lateral protrusive

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[JRogoff]

The answer is definetly "A". I had that exact question on my occulsion test yesterday.

 

[drPheta]

The answer is definetly "A". I had that exact question on my occulsion test yesterday.

Ok, I think I understand it now. Is it because they're not "drawing" in the cusp tip and that contact is actually on the outer surface of the buccal cusp? Either way, as long as I don't have my definition of working side and non-working side wrong.

 

[ItsGavinC]

For sure, remember this little tidbit:

Maxillary Working: Buccal
Maxillary Non-Working: Mesiolingual

Mandibular Working: Lingual
Mandibular Non-Working: Distobuccal


That movement is buccal, so you can tell that it's maxillary working without knowing anything else about the equation. There isn't anything else that it could possible be!

 

[HuyetKiem]

Ok, I think I understand it now. Is it because they're not "drawing" in the cusp tip and that contact is actually on the outer surface of the buccal cusp? Either way, as long as I don't have my definition of working side and non-working side wrong.

yes, you're rite. the interference is on the facial surface of the supporting cusp